Typical cellular communications are user-to-user calls. In these cellular calls, a first cellular user dials the directory number of a second user, who can be a cellular user or a landline user. Assuming the second user answers the call, a full-duplex communication takes place, where both the first user and the second user can send and receive voice signals to the other user. These voice signals can be sent and received simultaneously.
Dispatch systems are typically one-to-many communications. A dispatch call is typically initiated by a dispatcher who initiates a dispatch call to a group of users of the system. For example, a dispatcher for a taxi company may send out a dispatch request to all taxicab drivers asking for any driver available to pick up a patron at a particular address. The communication in a dispatch call is typically simplex or half-duplex, where the voice data travels in a single direction, typically from the dispatcher to the group of users.
One problem inherent in all dispatch systems occurs when multiple users respond to a dispatch message. In such scenarios, multiple users often respond simultaneously. In the example given above, multiple taxicab drivers may respond that they are willing and able to pick up the customer at the stated address. In such situations, the response from the multiple users is typically combined, which leads to the recipient of the multiple responses being unable to decipher them. Often, the dispatcher must send a second message requesting the users to resend their responses. The dispatcher may have to specifically state which user should respond first. This leads to a very inefficient utilization of resources.
In packet-based communication systems, the responses sent by the recipients of the original dispatch message are often interleaved. Interleaving refers to the process of arranging the order of packets from multiple users to form a data stream in which packets from one user are not contiguous. Although interleaving is effective in reducing the probability that a data error will disproportionately affect one user's communication, it can have other undesirable characteristics.
One problem that occurs in dispatch calls in packet-based communication systems is that the voice packets of replying users are mixed together. The mingled voice packets, when played, thereby often do not form an intelligible voice pattern, but rather an unintelligible mixture of the multiple respondents.
Therefore, a need exists for a method and apparatus for effectively sequencing data packets in a manner that is intelligible by the recipient of the data packets.